A145603 - cp's OEIS frontend

A145603 a(n) is the number of walks from (0,0) to (0,4) that remain in the upper half-plane y >= 0 using 2*n +2 unit steps either up (U), down (D), left (L) or right (R).

n	a(n)
1	1
2	35
3	720
4	12375
5	196625
6	3006003
7	45048640
8	668144880
9	9859090500
10	145173803500
11	2136958387520
12	31479019635375
13	464342770607625
14	6861343701121875
15	101583106970400000
16	1507019252941540800

[1, 35, 720, 12375, 196625, 3006003, 45048640, 668144880, 9859090500, 145173803500, 2136958387520, 31479019635375, 464342770607625, 6861343701121875, 101583106970400000, 1507019252941540800]

cp's OEIS Frontend

A145603 a(n) is the number of walks from (0,0) to (0,4) that remain in the upper half-plane y >= 0 using 2*n +2 unit steps either up (U), down (D), left (L) or right (R).

Table of values

List of values